Grid plates for making positive and negative electrode plates of a conventional lead acid storage battery are made of Pb-Ca-Sn alloy or other like alloy. With such a conventional storage battery, both the positive and negative electrode grid plates carry legs formed to be of an equal width. There has been known a lead acid storage battery carrying plate assembly of positive and negative electrode plates made out of the grid plates fabricated as mentioned above, in which said plate assembly is placed in a battery container in such a manner that the negative and positive electrode plates may be rested on and supported by such a saddle disposed at the bottom surface of the battery container that is capable of absorbing the extension of the positive electrode plates.
However, it has been observed with the conventional storage battery that when it is in use, there occurs the extension of the positive electrode plate in particular and this positive electrode plate extension can only be absorbed unsatisfactorily by the saddle, thus causing warping of the positive electrode plate and other inconveniences which result in the internal shortcircuiting in the negative and positive electrode plates of the plate assembly. More specifically, the warped positive electrode plates cause shortcircuiting with the adjoining negative electrode plates, leading to the decreased capacity and shorter service life of the battery. This kind of the disadvantageous phenomenon takes place at an even more accelerated pace when the battery is used under a high temperature condition.
As a means of solving these problems, the saddles made of various expandable resin materials having different expansion ratios have been used in the storage batteries only to see the problems still remain unsolved. In view of the above, it is much desired to make available a means that can help improve the absorption effect with respect to the positive electrode extension.